Jane 3, 1886. ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
449 
cases a counter-attraction is provided to draw the unwelcome visitors to 
parts where their attention will be harmless : thu3 Impatiens has honey- 
glands on the leaves which are said to stop the ants on their way to the 
flower. 
Other insects than ants are also to be guarded against. Many flowers 
are capable of fertilisation by m ire than one species of insect, hut others 
are especially adapted only to one kind. In these the form of the flower, 
while affording facilities for the proper insect to receive its pollen upon 
•the proper region of its body, also presents obstacles to others which 
would be useless. The peculiar construction of the corolla in such cases 
serves as a protection to both nectar and pollen. This may be carried 
still further, access to the honey by other than the appropriate channel 
"being hindered hy chemical means. An instance of this is seen in the 
Alpine varieties of the Aconite, which are adapted for fertilisation by 
"bees. Instead of the insect inserting its proboscis into the flower from 
the front, so as to make it pa«s the stamens and pistil, one bee (Bombus 
mastrucatus) bites a hole in the back of the hood formed by the sepals, 
and abstracts the honey. The white variety of the flower is unprotected 
against the theft, but the other, blue in colour, has a nauseous, hitter 
taste, and so is let alone. 
Besides meeting the attacks of animals in these different ways, plants 
have to cope with other dangers, and require for these another system of 
defences, which are more associated with peculiarities of environment. 
They are assailed continually by varying conditions of climate and tem¬ 
perature, and have in many cases very curious modifications of structure 
and habit to correspond with these. A danger that threatens most plants, 
except in a few regions of the world, is that of having their pollen injured 
by rain. To meet this many varieties of form of corolla have been 
developed. Many have a loDg narrow tubular shape, the claws of the 
petals cohering together, while the free limbs can curve outwards in fine 
weather, hut arch over the tube when wet. Others have a campanulate 
form, with the base of the hell upwards, so that rain falling on the flower 
■cannot get near the stamens, but is shot off as by a roof. In others the 
stamens are covered over by development of another part of the flower, 
as in the Iris ; the filament of the stamen, too, may be broad, and bear 
the anther on its under surface, as in the Naiadacese. It is rather curious 
that flowers that produce large quantities of p lien have not such defences 
against this danger as those which form but little, while the most complete 
adaptations are found in the cases of plants that inhabit damp climates. 
Many flowers are defended by habit rather than structure. In wet 
weather they do not open their corollas at all, and not a few, even in fine 
weather, keep open for a very little while, only a few hours in many cases. 
Besides rain, other meteorological conditions are fraught with danger. 
One of the most commonly occurring is frost; and allied to this is the 
loss of heat by radiation during the night. The power of resistance to 
these conditions varies very much, but in many whose constitution makes 
them peculiarly susceptible to damage thereby there has been developed 
the so-called power of sleep. The term is no doubt a misnomer, but it 
has been adopted and associated with certain well-defined movements 
which the leaves of the plants per! rm at the close and at the beginning 
of day. The movements differ very greatly with different plants, but they 
bring about such a position of the leaves as will protect the upper surface 
from radiation. Some of them are of a very complex nature, particularly 
those shown by certain of the Leguminosoe, which have pinnate leaves. 
It is in this natural order that the property of sleep is most prevalent, 
■certain of the Oxalidaceae and their allies coming next to them. 
A similar mechanism protects very many plants from excess of sun¬ 
light, which is injurious to the chlorophyll. In bright sunshine the leaves 
«Bsume a position which has been called “ diurnal sleep.” In it they 
present their edges and not their faces to the light. In other leaves the 
chlorophyll corpuscles themselves move, taking up a position on the 
lateral walls of the cells rattier than on the front ones, or so placing 
themselves that their profile and not their surface is exposed to the sun. 
In some of the Alg®, as Mesocarpus and Yaucheria, this sensitiveness is 
■seen. 
Other protective devices may he seen by studying the adaptations of 
plants to their conditions of life. Thus the leaves of submerged plants are 
preserved from being broken by the currents of water by being minutely 
sub-divided, so that they adapt themselves easily to the motion, and do 
not oppose a resistance. Desert plants are protected from drought by the 
development of a succulent hat>it. Aerial parts of plants, again, are pro¬ 
tected in many cases from bei oming moistened by water by a deposition 
dn the cuticular layers of the epidermis of varying amounts of wax or 
resin.—( Nature .) 
NOTES ON HERBACEOUS PLANTS. 
Doronicums. —There are no more showy herbaceous plants than the 
Doronicums at the present time, with thGr masses of green foliage and 
bright yellow flowers. They flower from the beginning of April far into 
the summer, and make o >r herbaceous border look very gay. D. austria- 
cum is very pretty, and should be in every collection of herbaceous 
■plants ; it generally throws up its flowers to the height of 2 ieet. 
D. caucasicum is also a very useful species, although not such a bright 
yellow as D. austriacum. D. plantagineum excelsum is one of the best 
Doronicums with its fine bright yellow flowers. 
Gentianas. —When looking over the herbaceous borders the other 
day I was greatly struck by the beauty of that very old-fashioned plant, 
the Gentiana acaulis, with its beautiful rich blue cup-shape flowers, for 
there is scarcely any flower in cultivation that has such a rich blue colour. 
•G. acaulis alba is a lovely variety with white flowers ; G. septemfida is a 
d warf-growing species, with terminal heads of bright blue-bearded flowers ; 
G. Andrewsii is a very showy species from North America, with deep 
blue purple flowers ; G. Burseri is very attractive with its large yellow 
flowers with purple spots, not forgetting that little gem G. verna, with its 
brilliant blue flowers, about 2 or 3 inches high. Most of the Gentianas 
should be in every collection of hardy flowers of any pretension whatever, 
for they have a most distinc ive and attractive appearance. 
Di elytra SPEctabilis. —At the present time this is very attractive 
on the herbaceous border. This well-known plant is generally esteemed, 
both for its usefulness for decorating our greenhouses and conservatories 
in the early spring, and for our herbaceous border in the early summer. 
D. spectabilis alba, although not generally so well known, is a very hand¬ 
some variety with white flowers. D. eximea is a very pretty dwarf- 
growing species with drooping red flowers ; it is very useful both for the 
rockery and border.— An Outside Foreman. 
ANOTHER NEW BOILER. 
Messrs. Stanley & Todd's horizontal “ V ” tubular boiler is repre¬ 
sented in the annexed engravings, fig. 84 showing the elevation and fig. 85 
the section of the apparatus. As is apparent, it consists of a series of V 
or wedge-shaped tubes horizontally arranged with water bars of the same 
shape, the tubes or ribs being further covered with a hood or water jacket. 
Provision is made for cleaning every part of the boiler, and, as it is in 
sections, any repairs that may be needed can be readily carried oub In 
& 
arranging the boiler for working brickwork is not required, but without a 
non-conducting covering there would of necessity be a considerable escape 
of heat ; with it, little or none. Different sizes are made to heat from 
500 to 10,000 feet of 4-inch piping. The action of the fire on the different 
parts is plainly seen, and there can be no doubt the boiler will answer its 
purpose well. __ 
ROOTING THE HEADS OF LARGE CORDYLINES. 
Those who confine the roots of these plants within certain sized pots 
have but a poor conception of the strength and rapidity with which they 
